It is the long range purpose of this project to study the perinatal development of the functioning small intestine in normal and environmentally, nutritionally, and hormonally stressed animals. The topics of present interest which relate to the development of the metabolic energy producing processes are: (1) the establishment of the mitochondrial permeability characteristics and substrate shuttles for NADH in the intestinal mucosa of hamsters; (2) the developmental patterns of the shuttle enzymes; (3) the relative contribution of the segments and mucosa and serosa to these activities; (4) the development of pyruvate dehydrogenase in relation to the redox state of the intestine; and (5) the establishment of isolation techniques and culture conditions for crypt and tip cells from the mucosal wall.